The present disclosure relates to a motor driver and a control method, and more particularly relates to DC brushless motor driving control.
While a DC brushless motor is being driven at high speeds, the phase of the motor current may shift with respect to the phase of the motor due to an induced voltage generated in the motor and other factors to cause a decrease in efficiency, even though the motor is still drivable anyway. Thus, to cope with this problem, a known driver attempts to improve the efficiency of a motor to use by recording its characteristic in advance and by performing phase compensation according to its drive frequency.
FIG. 33 is a block diagram illustrating a configuration for a conventional motor driver/control method. The motor driver/control method shown in FIG. 33 comprises: a correction value table block 2502 for outputting, in response to a correction value selection signal 2501, a correction value from a correction value table on which the correction value has been recorded in advance in accordance with the characteristic of the motor to use; the function of detecting the phase of the motor in which a motor drive period is output in response to a motor phase signal 2503 (illustrated as a motor phase detector 2504); and the function of computing a motor applied voltage signal 2506 based on the correction value and motor drive period provided (illustrated as a motor applied voltage calculator 2505).
FIGS. 34A and 34B are timing charts illustrating how the conventional motor driver/control method works. In these timing charts, the motor is supposed to be a triphase brushless motor as an example. In these drawings, output terminals to drive the motor are identified by U, V, and W, and their associated Hall signals are identified by HU, HV, and HW, respectively. If no phase compensation is performed, the motor current phase has a phase lag with respect to the Hall signal as shown in FIG. 34A. On the other hand, if phase compensation is performed, the motor current phase maintains an appropriate phase difference with respect to the Hall signal.
See, for example, Japanese Unexamined Patent Publication No. 2008-125246.
However, such phase compensation is performed with the characteristic of the motor recorded in advance after the characteristic of the motor has been adjusted to a particular motor constant. Thus, if the same motor driver/control method is applied to a motor with a different motor constant, then the drive efficiency will decrease. That is why such a driver/method lacks in broad applicability.
In view of the foregoing background, the present disclosure provides a motor driver and control method which contributes to maintaining high drive efficiency and which is applicable broadly enough to avoid depending on the characteristic of any particular motor.